The present invention is directed to an apparatus and method for damping vibration of a vehicle part, such as a vehicle steering wheel or an electric motor.
Vehicle parts, such as a vehicle steering wheel or an electric motor, can be prone to unwanted vibration. The steering wheel is prone to vibration because it is mounted at one end of the steering column which acts as a cantilever. Vibratory inputs, such as, for example, vibration resulting from an engine imbalance or from the driving surface, are transmitted through the steering shaft to the steering wheel, where the vibration is felt by the driver of the vehicle.
In order to reduce the amplitude of steering wheel vibration felt by the vehicle driver, it is known to attach a tuned mass damper to the steering wheel to counteract the vibration. A tuned mass damper is a discrete oscillating device commonly formed by a spring-like element, such as an elastomeric member, and a mass arranged in parallel. The tuned mass damper is tuned to an excitation frequency that is resonant with the natural frequency of the steering wheel/column assembly. Vibration of the steering wheel is suppressed by an inertial force created by the tuned mass damper moving out of phase with the vibration of the steering wheel. One limitation, however, of a tuned mass damper is that the tuned mass damper is tuned to a relatively narrow frequency range and thus does not damp vibration outside the narrow frequency range. Hence, a need exists for a vibration damping apparatus for a vehicle steering wheel that is effective across a relatively broad frequency range. Such a damping apparatus could also be adapted to damp vibration of various other parts in a vehicle, such as an electric motor.
Electric motors can operate at a single rotational speed, or can operate over a range of rotational speeds. An electric motor, such as is used in connection with an electric powered hydraulic system, may be structurally excited when the operation speed (or a multiple thereof) corresponds with a model frequency of the motor, which generates unwanted vibration and/or noise. It is desirable to provide an apparatus for damping the structural mode""s of an electric motor and thereby reduce the amplitude of resonant vibrations and noise.
The present invention is an apparatus for damping vibration of a vehicle part. The apparatus comprises at least one container having a chamber defined by at least one interior wall. The at least one container is associated with the vehicle part. A plurality of particles is disposed in the chamber. The particles, when at rest, occupy a first portion of the chamber and define an unoccupied second portion of the chamber. The particles move back and forth between the first and second portions of the chamber in response to vibration of the vehicle part and collide with each other and with the at least one interior wall defining the chamber to damp the vibration of the vehicle part through a momentum exchange between the particles and the at least one interior wall, through inter-particle dry friction and dry friction between the particles and the at least one interior wall, and through plastic deformation of the particles.
In accordance with another aspect of the present invention, an apparatus comprises a vehicle steering assembly and at least one container associated with the vehicle steering assembly. The at least one container has a chamber defined by at least one interior wall. A plurality of particles is disposed in the chamber. The particles, when at rest, occupy a first portion of the chamber and define an unoccupied second portion of the chamber. The particles move back and forth between the first and second portions of the chamber in response to vibration of the vehicle steering assembly and collide with each other and with the at least one interior wall defining the chamber to damp the vibration of the vehicle steering assembly through a momentum exchange between the particles and the at least one interior wall, through inter-particle dry friction and dry friction between the particles and the at least one interior wall, and through plastic deformation of the particles.
In accordance with yet another aspect of the present invention, an apparatus for use in a vehicle comprises an electric motor and at least one container associated with the electric motor. The at least one container has a chamber defined by at least one interior wall. A plurality of particles is disposed in the chamber. The particles, when at rest, occupy a first portion of the chamber and define an unoccupied second portion of the chamber. The particles move back and forth between the first and second portions of the chamber in response to vibration of the electric motor and collide with each other and with the at least one interior wall defining the chamber to damp the vibration of the electric motor through a momentum exchange between the particles and the at least one interior wall, through inter-particle dry friction and dry friction between the particles and the at least one interior wall, and through plastic deformation of the particles.
The present invention also provides a method for damping vibration of a vehicle part. According to the inventive method, at least one container having a chamber defined by at least one interior wall is provided. The at least one container is associated with the vehicle part. The chamber in the at least one container is partially filled with a plurality of particles so that a first portion of the chamber is occupied by the particles when at rest, while a second portion of the chamber remains unoccupied. Vibration of the vehicle part is damped through movement of the particles back and forth between the first and second portions of the chamber in response to the vibration of the vehicle part. The particles collide with each other and with the at least one interior wall defining the chamber to damp the vibration of the vehicle part through a momentum exchange between the particles and the at least one interior wall, through inter-particle dry friction and dry friction between the particles and the at least one interior wall, and through plastic deformation of the particles.
In accordance with yet another aspect of the present invention, a method for damping vibration of a vehicle steering assembly is provided. According to the inventive method, at least one container having a chamber defined by at least one interior wall is provided. The at least one container is associated with the vehicle part. The chamber in the at least one container is filled 70% to 98% with a plurality of particles so that a first portion of the chamber is occupied by the particles when at rest, while a second portion of the chamber remains unoccupied. Vibration of the vehicle steering assembly is damped through movement of the particles back and forth between the first and second portions of the chamber in response to the vibration of the vehicle steering assembly. The particles collide with each other and with the at least one interior wall defining the chamber to damp the vibration of the vehicle steering assembly through a momentum exchange between the particles and the at least one interior wall, through inter-particle dry friction between the particles and the at least one interior wall, and through plastic deformation of the particles.
In accordance with still another aspect of the invention, a method for damping vibration of an electric motor in a vehicle is provided. According to the inventive method, at least one container having a chamber defined by at least one interior wall is provided. The at least one container is associated with the electric motor. The chamber in the at least one container is filled 70% to 98% with a plurality of particles so that a first portion of the chamber is occupied by the particles when at rest while a second portion of the chamber remains unoccupied. Vibration of the electric motor is damped through movement of the particles back and forth between the first and second portions of the chamber in response to the vibration of the electric motor. The particles collide with each other and the at least one interior wall defining the chamber to damp the vibration of the electric motor through a momentum exchange between the particles and the at least one interior wall, through inter-particle dry friction and dry friction between the particles and the at least one interior wall, and through plastic deformation of the particles.